Absorption Coefficient and Intermolecular Vibrations in the СО–Ar System

Absorption in the 1–0 band of CO broadened by Ar is examined using the asymptotic line-wing theory (ALWT). A semiclassical expression is derived for the line shape, where the motion of the centers of mass is considered classical and other variables remain quantum. The line shape parameters are fitted to reach agreement between calculated and experimental data on the absorption in the CO band wing. The classical potential parameters are found from the temperature dependence of the second virial coefficient. A qualitative agreement is found between the quantum potential parameters and intermolecular potential surfaces from quantum-chemical calculations.